The find could completely rewrite what we know about the Mayan civilisation.

Archaeologists are extremely excited.

Using state-of-the-art laser technology, archaeologists uncovered over 60,000 previously unknown Mayan structures deep in the Guatemalan jungle, including foundations for houses, military fortifications, and elevated causeways.

Archaeologists could barely contain their excitement about the ground-breaking find.

“I think this is one of the greatest advances in over 150 years of Maya archaeology,” Stephen Houston, an archaeologist at Brown University with decades of experience studying Mesoamerican cultures told the BBC.

“This is HOLY $HIT territory,” Sarah Parcak, a professor of archaeology at the University of Alabama and a National Geographic fellow who was not involved in the project, tweeted.

“We’ll need 100 years to go through all [the data] and really understand what we’re seeing,” Francisco Estrada-Belli, a Tulane University archaeologist, told National Geographic.

Lidar technology is a game-changer for archaeologists

Lidar, the technology used by the researchers to uncover the structures, uses millions of laser pulses to detect structures underneath the dense jungle foliage that are almost invisible to the naked eye. The instrument is mounted on aircraft, like a light aeroplane or a helicopter, and the wavelengths of light are measured as they bounce back – much like a ship uses sonar to gauge depth.

These signals are then used to produce detailed, three-dimensional topographic maps of the ground underneath the jungle’s vegetation and layers of sediment. Skilled observers can pick out manmade structures, and further analysis can tell the researchers the size of the structure, and when it may have been built in order to build a detailed timeline of Mayan history. And, it saves a lot of time trudging around the jungle. In decades of examining these sites in the remote Petén region of Guatemala, archaeologists didn’t have a clue these structures were right beneath their feet.

The structures uncovered by the team suggest that instead of living in isolated city-states, the Mayans controlled huge territories with millions of people, industrial-scale food production, and sophisticated trade networks – on the scale of Ancient Greece or Rome.

The Mayan civilisation could have had millions more inhabitants than archaeologists previously thought

Thomas Garrison, an archaeologist on the project, believes the findings indicate that previous population estimates for the Mayans were “grossly underestimated,” and could, in fact, be more than three or four times what researchers previously thought, according to the BBC.

Some of the structures the archaeologists discovered were hiding in plain sight. Garrison described how he came 150 feet away from one of the fortresses discovered by the Lidar scan on an excavation mission in 2010, but never found it. The Lidar images also showed a seven-story pyramid that had practically been swallowed by the jungle’s vegetation.

“With this new data it’s no longer unreasonable to think that there were 10 to 15 million people there – including many living in low-lying, swampy areas that many of us had thought uninhabitable,” Francisco Estrada-Belli, the lead researcher on the project, told National Geographic.

At the Mayan civilisation’s zenith, some 1,500 years ago, emissaries from different cities may have used the elevated causeways to trade goods like corn, or even for military conquest. The researchers found evidence that the Mayans had expertly altered the landscape to control the flow of precipitation to water crops and keep floodwaters from damaging buildings.

Other archaeologists on the project waxed more poetic about the way the find could rewrite what we know about where advanced societies first flourished.

“We’ve had this western conceit that complex civilizations can’t flourish in the tropics, that the tropics are where civilizations go to die,” Marcello Canuto, a Tulane University archaeologist told National Geographic.

“We now have to consider that complex societies may have formed in the tropics and made their way outward from there,” he added.

The National Geographic Channel is airing a one-hour special about the Lidar finds, called “Lost Treasures of the Maya Snake Kings,” on February 6 at 9 p.m.